This disclosure relates generally to railroad grade crossings, and more particularly to an improved vehicular supporting structure formed by a plurality of precast slabs adapted to be assembled at the job site.
Heretofore, various vehicular supporting structures have been proposed for installation at railroad grade crossings. Generally speaking, the structures themselves have been constructed from such materials as wood, concrete, steel, and various rubber compositions. Structures of wood and concrete are installed for substantially the same unit cost, but a disadvantage with respect to the former, is the cost of maintenance whereas the disadvantage of the latter, is the tendency to break-up or crack when subjected, over a period of time, to railroad and vehicular traffic. Steel structures are installed for approximately twice the cost relative to structures formed of wood and concrete, and the structures formed from the rubber compositions have been found to be about three (3) times more expensive than the steel or about six (6) times more expensive than structures formed of wood and concrete.
In the subject invention, the structure is formed by a plurality of reinforced concrete slabs with each including a pair of rail sections secured on opposite lateral sides thereof. The rail sections expand and contract in direct proportion with the running rails with minimum effect on the reinforced concrete. For a disclosure of a generally analogous slab, reference may be had to U.S. Letters Pat. No. 3,341,123 to M. Holthausen, that patent being incorporated herein by reference. The unit cost of the structure is comparable to that of wood or concrete and correspondingly, less expensive than either of the structures utilizing steel or the rubber composition. It is, therefore, a general object of the subject invention to provide a vehicular supporting structure which is highly competitive relative to all heretofore known installations at grade crossings.
Another disadvantage of prior known vehicular supporting structures for railroad grade crossings resides in the fact that the structure itself is connected to the railroad ties. As will be appreciated, railroad ties are irregularly spaced at intervals which have been found to vary between 18 to 26 inches thereby necessitating either advance track preparation or the installation of special cross ties to accommodate the installation of the supporting structure. Moreover, the outer surface of railroad ties are irregular and can require the use of special pre-fabricated shims to facilitate locating the slabs of the supporting structure relative to the elevation of the running rails. In the subject invention, the slabs are connected to the running rails themselves and supported by a plurality of deformable pads preferably located on every other railroad tie. Each pad is formed by filling a relatively flexible bag with a mortar of putty-like consistency which is adapted to compress, preform, and set whereby to accommodate all inconsistencies and irregularities of the individual ties. During the period while the pads are setting, the individual slabs are supported by one or more temporary standard shim elements which are supported by alternate or every other railroad tie relative to the ties supporting the pads. It is, therefore, a primary object of the subject invention to provide a vehicular supporting structure of the above indicated character which obviates the need for special advance track preparation including the installation of any specially formed cross ties or special pre-fabricated shims.
It is another object of the present invention to provide a vehicular supporting structure for a railroad grade crossing which is easily insulated from the running rails to permit installation thereof in signal control sections of track.
It is a further object of the present invention to provide a vehicular supporting structure of the above described character which can be also adapted for installation with multiple, switch, and curved sections of track.
Other objects, features, and advantages of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings.